Danger #4: Overpopulation
This is another serious danger threatening the Earth and humanity as a whole. The human population is constantly rising at an exponential rate. The time when the Earth wouldn’t be able to support us anymore is quite near.
Overpopulation is also aggravating an already serious problem threatening our civilisation: resource depletion. Our civilization relies on fossil fuels for transportation and various minerals for manufacture. These resources are not infinite. One day there would be no more left. And unfortunately this day seems to be quite near.
Another consequence of overpopulation is the increase of poverty in the world. This is due to the fact that the population growth is much higher in the poor countries than in the rich ones.
Only the colonization of space on a massive scale would resolve all these problems in the long term. There is more territory and ressources in space than we will ever need.